Original and article manufacturing method using same

ABSTRACT

The original of the present invention has a pattern to be transferred. For example, the original of the present invention is a mold for use in an imprint apparatus or a mask for use in an exposure apparatus. The original has a negative effective Poisson&#39;s ratio. Alternatively, the original has an effective Poisson&#39;s ratio smaller than that of a quartz glass plate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an original (for example, a mold to beused in an imprint apparatus or a mask to be used in an exposureapparatus) and an article manufacturing method using the same.

2. Description of the Related Art

As the demand for microfabrication of semiconductor devices increases,not only is there a conventional photolithography technique, but thereis also a microfabrication technique in which a mold (original) and anuncured resin on a substrate are pressed against each other to therebyform a resin pattern, which corresponds to a fine concave and convexpattern formed on the mold, on the substrate. This technique is alsoreferred to as an “imprint technique”, by which a fine structure on theorder of a few nanometers can be formed on the substrate. One example ofimprint techniques includes a photo-curing method. Firstly, thephoto-curing method applies an ultraviolet curable resin (imprint resin,photocurable resin) to the shot area (imprint area) on the substrate.Next, the resin (uncured resin) and a mold are pressed against eachother. After the ultraviolet curable resin is irradiated withultraviolet light for curing, the cured resin is released from the mold,whereby a resin pattern is formed on the substrate.

An imprint apparatus employing the aforementioned technology correctsthe shape of a mold using a shape correction mechanism depending on theshape of a pattern on a substrate. At this time, shape correctionincludes not only simple magnification corrections but also correctionsin which the shape of a mold is deformed into another shape such as aparallelogram or a trapezoid. In general, the shape correctionmechanisms are installed in plural locations on the outer circumferenceportion of a mold. Each of the shape correction mechanisms imparts anexternal force to a mold from the outer circumference portion to therebycause the mold itself to be deformed, so that the pattern shape formedon the mold is corrected. The pattern shape affects the superpositionaccuracy of the patterns. In particular, for the correction of thepattern shape using a shape correction mechanism, a highly accuratecorrection on the order of less than a few nanometers is required inorder to accommodate the recent trend toward pattern micronization. As adevice for correcting the shape of a pattern, such as a shape correctionmechanism, Japanese Patent Laid-Open No. 2008-504141 discloses a devicethat applies a compressive force to the mold-side surface to therebyperform magnification correction. The device is constituted by anactuator, a link mechanism, and the like. The devices are installed inplural locations so as to enclose the outer circumference portion of amold.

However, in the device disclosed in Japanese Patent Laid-Open No.2008-504141, when a force is applied to a mold from the outercircumference portion thereof (for example, when a pattern is correctedinto a trapezoidal shape), a large correction error may occur. Here,assume the case where a mold is formed of quartz having a positivePoisson's ratio. In this context, the device disclosed in JapanesePatent Laid-Open No. 2008-504141 applies a compressive force to one basefor shortening the length thereof and a tensile force to the other basefor extending the length thereof. In this case, the shortened base ofthe mold is bent inward and the extended base thereof is bent outwarddue to the effect of Poisson's ratio. Thus, a correction error newlyoccurs due to the shape correction of a pattern into a trapezoidalshape.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides, for example, an originalthat is advantageous in terms of causing it to be deformed into a targetshape.

According to a first aspect of the present invention, an original havinga pattern to be transferred is provided that has a negative effectivePoisson's ratio.

According to a second aspect of the present invention, alight-transmissive original has a pattern to be transferred, wherein theoriginal has an effective Poisson's ratio smaller than that of a quartzglass plate.

The present invention can provide, for example, an original that isadvantageous in terms of causing it to be deformed into a target shape.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the configuration of an imprintapparatus according to an embodiment of the present invention.

FIG. 2A is a perspective view illustrating a mold according to a firstembodiment as seen from the wafer side.

FIG. 2B is a perspective view illustrating a mold according to the firstembodiment as seen from the mold base side.

FIG. 2C is an enlarged plan view illustrating the auxetic structure of amold according to the first embodiment.

FIG. 3A is a schematic view illustrating a correction of the trapezoidalcomponent of a pattern.

FIG. 3B is a schematic view illustrating another correction of thetrapezoidal component of a pattern.

FIG. 3C is a schematic view illustrating another correction of thetrapezoidal component of a pattern.

FIG. 4A is a schematic view illustrating the shape of a mold accordingto a second embodiment.

FIG. 4B is a schematic view illustrating another shape of a moldaccording to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will now bedescribed with reference to the accompanying drawings.

(Imprint Apparatus)

First, a description will be given of the configuration of an imprintapparatus according to an embodiment of the present invention. FIG. 1 isa schematic view illustrating the configuration of an imprint apparatus.The imprint apparatus according to the present embodiment is aprocessing apparatus that transfers the pattern of a mold to a wafer (asubstrate), i.e., a substrate to be processed, which is used for asemiconductor device manufacturing process, and is an apparatus thatemploys a photo-curing method among the imprint techniques. In thefollowing drawings, a description will be given in which the Z axis isoriented in parallel to the irradiation axis of ultraviolet light for amold, the X axis is oriented in the direction in which a wafer moveswith respect to a mold base to be described below in a planeperpendicular to the Z axis, and the Y axis is oriented in the directionperpendicular to the X axis. An imprint apparatus 1 of the presentinvention includes an illumination unit 2, a mold holding unit 4, awafer stage 6, an application unit 7, a mold conveyance unit 8, and acontroller 9.

The illumination unit 2 is an illumination unit configured to irradiatethe mold 3 with an ultraviolet light 10 during imprint processing. Theillumination system 2 is constituted by a light source and a pluralityof optical elements that adjust ultraviolet light emitted from the lightsource to a light suitable for imprint. The mold holding unit 4 is aholding device that holds and fixes the mold 3. The mold holding device4 includes a shape correction mechanism 11 that corrects the patternformed on the mold 3 to a desired shape by applying a compressive forceto the mold 3, and a mold base 12 that draws and holds the mold 3 by asuction force or an electrostatic force. The shape correction mechanism11 consists of a plurality of driving mechanisms that are arranged so asto respectively face four side surface (peripheral side surface) areasof the mold 3. The correction components of the pattern to be correctedby the shape correction mechanism 11 include a magnification component,a parallelogram component, a trapezoidal component, a barrel component,a pincushion component, and the like. The configuration of the shapecorrection mechanism 11 is not limited thereto. For example, the shapecorrection mechanism 11 may apply a tensile force to the mold 3 or maydrive the mold base 12 itself so as to impart a shearing force to thecontact surface between the mold 3 and the mold base 12.

The mold holding unit 4 further includes a base driving mechanism (notshown) that drives the mold base 12. More specifically, the base drivingmechanism is a driving system that drives the mold base 12 in theZ-axial direction so as to press the mold 3 against the ultravioletcurable resin 12 formed on the wafer 5. An actuator employed for thedriving mechanism is not particularly limited as long as it can drive atleast in the Z-axial direction. A linear motor, an air cylinder, and thelike can be employed. Alternatively, in order to perform a mold-releaseoperation with high precision so as to prevent the cured ultravioletcurable resin from being damaged when a mold-release operation forreleasing the mold 3 from the ultraviolet curable resin is performed, anactuator may be employed to carry out a coarse operation and a microoperation in a divided manner. The imprint operation and themold-release operation may be realized by driving the mold 3 in theZ-direction as described above or may also be realized by driving thewafer stage 6 (the wafer 5) in the Z-direction.

The wafer 5 is a substrate to be processed consisting of, for example, asingle crystal silicon, and an ultraviolet curable resin (hereinafterreferred to simply as “resin”), which serves as a molding section, isapplied on the treatment surface. Also, the wafer stage 6 is a substrateholding unit configured to hold the wafer 5 by vacuum suction and befreely moveable in the XY plane. As an actuator for driving the waferstage 6, a linear motor can be employed, but this is not particularlylimiting. The application unit (dispenser) 7 is an application unitconfigured to apply an uncured resin on the wafer 5. The resin is aphotocurable resin having curing characteristics that is cured byultraviolet light, and is appropriately selected depending on the typeof a semiconductor device to be manufactured. Furthermore, the moldconveyance unit 8 is a conveyance unit configured to convey the mold 3to thereby place the mold 3 on the mold base 12.

The controller 9 is a controller configured to control the operation,adjustment, and the like of the components of the imprint apparatus 1.The controller 9 is constituted by a computer, a sequencer, and the likehaving a magnetic storage medium and the like that is connected to thecomponents of the imprint apparatus 1 through a circuit, and executescontrol of the components by a program or a sequence. Note that thecontroller 9 may be integrated with the imprint apparatus 1, or may beinstalled at a location separate from the location where the imprintapparatus 1 is installed to thereby be controlled remotely.

Next, a description will be given of imprint processing to be performedby the imprint apparatus 1. Firstly, the controller 9 causes the wafer 5to be placed and fixed on the wafer stage 6, and then moves the waferstage 6 to the application position of the application unit 7. Then, theapplication unit 7 applies a resin (uncured resin) to a predeterminedshot (treatment area) of the wafer 5. Next, the controller 9 moves thewafer stage 6 such that the application surface on the wafer 5 ispositioned below the mold 3. Next, the controller 9 performs alignmentof the imprint surface of the mold 3 with the application surface on thewafer 5 and shape correction of the mold 3 using the shape correctionmechanism 11, and then drives a base driving mechanism to therebyimprint the mold 3 into the resin 12 that has been applied on the wafer5. At this time, the resin flows along the pattern formed on the mold 3by imprinting with the mold 3. Under this condition, the illuminationunit 2 emits the ultraviolet light 10 from the rear side (upper side) ofthe mold 3, and the resin is cured by the ultraviolet light 10 that hasbeen transmitted through the mold 3. Then, after the resin is cured, thecontroller 9 again drives the base driving mechanism to thereby releasethe mold 3 from the wafer 5. By the aforementioned steps, a threedimensionally shaped resin layer following the pattern of the mold 3 isformed on the shot surface of the wafer 5.

First Embodiment

FIGS. 2A to 2C are schematic views illustrating the shape of the mold 3according to the first embodiment of the present invention. Inparticular, FIG. 2A is a perspective view illustrating the mold 3 asseen from the wafer 5 side (the surface side), and FIG. 2B is aperspective view illustrating the mold 3 as seen from the mold base 12side (the rear side) facing the wafer 5 side. The mold 3 has arectangular shape at an outer periphery thereof and is an original(mold) in which a predetermined pattern (e.g., the concave and convexpattern of a circuit pattern or the like) is three-dimensionally formedon the surface facing the wafer 5. The surface of the pattern isprocessed at high flatness so as to maintain the adhesion between thesurfaces of the pattern and the wafer 5. Note that the material of themold 3 is a material such as quartz (Poisson's ratio: 0.16) or the likethrough which ultraviolet light can pass.

As shown in FIG. 2A, the mold 3 is constituted by a base portion 20serving as a main body portion, and a mesa portion (convex portion) 21which protrudes in the center portion of the surface side of the baseportion 20 and on which a pattern (not shown) is formed. The peripheraldimension and the height dimension of the mesa portion 21 are determinedby a desired pattern shape. Also, as shown in FIG. 2B, the mold 3 (atleast a part of the base portion 20) has an auxetic structure portion 22provided on the back surface side thereof. The auxetic structure portion22 is a structure having a negative Poisson's ratio. Poisson's ratio iscategorized into two types: Poisson's ratio indicated by the materialitself and Poisson's ratio indicated by the structure (body). Here, theterm “effective Poisson's ratio” is defined with respect to an original.The expression “effective Poisson's ratio is negative” with respect toan original means that the original has a structure in which a portionincluding a pattern to be transferred (e.g., the mesa portion 21) isshrunk and deformed in the Y-direction when a compressive force isapplied in the X-direction to the base portion (e.g., the base portion20 shown in FIGS. 2A and 2B). The aforementioned expression also meansthat an original has a structure in which a portion including a patternto be transferred is expanded and deformed in the Y-direction when atensile force is applied in the X-direction to the base portion. Theexpressions “effective Poisson's ratio is positive” and “effectivePoisson's ratio is zero” are defined in a similar manner.

Here, an original having a negative effective Poisson's ratio may berealized by the fact that at least a portion of a mold has a structurehaving a negative Poisson's ratio, such as an auxetic structure. Also,an original having a negative effective Poisson's ratio may be realizedby the fact that at least a portion of a mold has a material having anegative Poisson's ratio, such as cristobalite. When a photo-imprintapparatus illuminates a photo (ultraviolet light) curable resin withlight via a mold, it is advantageous that the original (mold) istransparent to light. In this case, a structure that is formed of atransparent material and has a negative Poisson's ratio may be useful.This also applies to a transmission-type original (transmission-typemask) for use in an exposure apparatus. Also, an original (mold) for usein a thermal imprint apparatus and a reflection-type original(reflection-type mask) for use in an exposure apparatus do not need tobe transparent to light, and thus, a material having a negativePoisson's ratio, such as cristobalite, may be useful. While an originalhaving a negative effective Poisson's ratio has been described above,the original does not necessarily have a negative effective Poisson'sratio. An original having an effective Poisson's ratio smaller than thatof the conventional original may also be employed. For example, withrespect to a light transmissive original such as an original (photoimprint original) for use in a photo-imprint apparatus, atransmission-type original for use in an exposure apparatus, and thelike, an original having an effective Poisson's ratio smaller than thatof a conventional original made of quartz (quartz glass plate) may alsobe employed. Such an original may be realized by the fact that a lighttransmissive original includes at least either one of a structure havinga negative Poisson's ratio or a material having a negative Poisson'sratio.

Next, an example of the auxetic structure according to the presentembodiment will be described. FIG. 2C is an enlarged plan viewillustrating the auxetic structure portion 22. The auxetic structureportion 22 has a plurality of hollowed portions 24 that are formed witha constant thickness (depth) from the Z-direction while leaving a wallportion 23 (FIG. 2B) with a constant width on the outer circumferenceportion of the base portion 20 at the back surface side thereof. Acontinuous rib portion 25 with a constant width is formed by thehollowed portions 24, and thus, the auxetic structure portion 22 is astructure having a negative effective Poisson's ratio. For reducing theeffective Poisson's ratio, it is desirable that the thickness of thehollowed portion 24 be more than twice the thickness of the mesa portion21. In the present embodiment, as shown in FIG. 2C, the formed ribportion 25 has a shape in which a plurality of ridge-like rib portionsare continuously formed in the X-direction and the vertexes of theridge-like rib portions are connected to each other in the Y-directionwhen viewed from the Z-direction. It should be noted that, in thepresent embodiment, the auxetic structure portion 22 may be of anystructure having a negative effective Poisson's ratio, and is notlimited to the shape as shown in FIG. 2C.

Next, a description will be given of the deformation of the mold 3 whenthe shape correction of the pattern formed on the mold 3 having theauxetic structure portion 22 is made by the shape correction mechanism11. In the present embodiment, the effective Poisson's ratio of the baseportion 20 is negative. Thus, when the shape correction mechanism 11applies a compressive force to the mold 3 in the X-direction from theperipheral side surface of the mold 3, the mesa portion 21 formed on thebase portion 20 is deformed in the Y-direction (shrinkage direction). Incontrast, when the shape correction mechanism 11 applies a tensile forceto the mold 3 in the X-direction from the peripheral side surface of themold 3, the mesa portion 21 is deformed in the Y-direction (expansiondirection). In other words, by making the effective Poisson's ratio ofthe base portion 20 negative, the Poisson's ratio of the mesa portion 21on which a pattern is formed is also substantially negative. In thisway, by making the Poisson's ratio of the mesa portion 21 negative, thecorrection residual of the trapezoidal component of the pattern may bereduced.

Each of FIGS. 3A to 3C is a schematic view illustrating the deformationof the mesa portion 21 as viewed from the Z-direction when thetrapezoidal component of the pattern (the mesa portion 21) is correctedonly by a force applied from the peripheral side surface of the mold 3.In FIGS. 3A to 3C, the trapezoid shown by a broken line 30 is the idealtrapezoidal shape to be the target of when the trapezoidal component ofthe pattern is corrected. In contrast, a solid line 31 shown in FIG. 3Aindicates the corrected shape of the mesa portion 21 when the Poisson'sratio of the mesa portion 21 is positive, a solid line 32 shown in FIG.3B indicates the corrected shape of the mesa portion 21 when thePoisson's ratio of the mesa portion 21 is zero, and a solid line 33shown in FIG. 3C indicates the corrected shape of the mesa portion 21when the Poisson's ratio of the mesa portion 21 is negative. In FIGS. 3Ato 3C, as the shape represented by each of the solid lines 31 to 33 iscloser to the shape represented by the broken line 30, such a shape iscloser to the target trapezoidal shape, that is to say, it means thatthe correction error of the trapezoidal component is small. Thus, asshown in FIG. 3C, the shape having a negative Poisson's ratio, which isrepresented by the solid line 33, is the closest to the shaperepresented by the broken line 30, and thus, it can be seen that thecorrection error of the trapezoidal component is small.

As described above, according to the mold 3 of the present embodiment,at least a partial structure thereof has a negative effective Poisson'sratio, and thus, the shape correction mechanism 11 may preferably deformthe pattern shape formed on the mesa portion 21 into the target shape.Consequently, the shape correction mechanism 11 may particularly reducethe correction error of the trapezoidal component of the pattern inaddition to the correction error of the magnification component,parallelogram component, and the like of the pattern. Also, according tothe mold 3, only the base portion 20 has the auxetic structure portion22 even when the mesa portion 21 does not have an auxetic structure, andthus, the effect of the present invention may be provided.

Second Embodiment

Next, a description will be given of a mold according to the secondembodiment of the present invention. FIG. 4A is a schematic viewillustrating the shape of the mold of the present embodiment which is amodification of the mold 3 according to the first embodiment, and FIG.4B is a perspective view corresponding to FIG. 2B illustrating the mold3 of the first embodiment. Firstly, although the mold 3 includes theauxetic structure unit 42 formed over the entire back surface of thebase portion 20, a mold 40 shown in FIG. 4A includes an auxeticstructure unit 42 that is provided near the center of the back surfaceof a base portion 41, that is, only at the location corresponding to amesa portion (not shown) formed on the surface side of the base portion41. With this arrangement, the same effects as those in the firstembodiment can be obtained. In addition, a wide area of flat portion tobe used for holding the mold 40 by means of, for example, a vacuumpressure or an electrostatic pressure may be set on the back surface ofthe mold 40. Although the region in which the auxetic structure portion22 is formed is of circular shape as shown in FIG. 4A, the region may beof polygonal shape such as rectangular shape or the like.

Furthermore, a mold 50 shown in FIG. 4B includes an auxetic structureunit 52 that is provided near the center of the back surface of a baseportion 51 as in the mold 40 shown in FIG. 4A and of which the height isone stage lower than that of a peripheral flat portion. With thisarrangement, the same effects as those provided by the mold 40 may beobtained. In addition, a mesa portion (not shown) formed on the surfaceside of the base portion 51 is readily deformed, and thus, a resin maybe efficiently filled in the pattern formed on the mesa portion duringan imprint operation. The same effects can be obtained even when theauxetic structure unit 52 of the mold 50 is limited to the positioncorresponding to a part of a lower region, that is, a mesa portionformed on the surface side instead of the fact that the auxeticstructure unit 52 is formed on the entire lower region which is onestage lower than a peripheral flat portion.

While, in the foregoing embodiment, an auxetic structure unit isprovided on the back surface side of a mold in order to make theeffective Poisson's ratio of the mold negative, the present invention isnot limited thereto. For example, instead of employing quartz as in theforegoing embodiment, the material constituting the mold may be amaterial having a Poisson's ratio smaller than that of quartz. In thiscase, the auxetic structure unit does not need to be formed on the backsurface side of the mold. Examples of such material having a Poisson'sratio smaller than that of quartz include cristobalite.

Furthermore, while, in the foregoing embodiment, a description has beengiven of the original of the present invention as a mold for use in animprint apparatus, the present invention is not limited thereto. Forexample, the original of the foregoing embodiment may also be applicableto a mask for use in an exposure apparatus such as so-called scanner,stepper, or the like.

(Article Manufacturing Method)

A method of manufacturing devices (a semiconductor integrated circuitelement, liquid crystal display element, and the like) as an articleincludes a process for transferring (forming) a pattern on a substrate(a wafer, glass plate, or film-like substrate) using the aforementionedimprint apparatus. Furthermore, the manufacturing method can include aprocess for etching the substrate on which the pattern is transferred.Note that upon manufacturing other articles such as patterned media(recording media) or optical elements, the manufacturing method caninclude other process for processing the substrate on which the patternis transferred in place of etching. The article manufacturing method ofthis embodiment has an advantage, as compared with a conventionalarticle manufacturing method, in at least one of performance, quality,productivity and production cost of an article.

While the embodiments of the present invention have been described withreference to exemplary embodiments, it is to be understood that theinvention is not limited to the disclosed exemplary embodiments. Thescope of the following claims is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures and functions.

This application claims the benefit of Japanese Patent Application No.2010-198432 filed Sep. 6, 2010 which is hereby incorporated by referenceherein in its entirety.

What is claimed is:
 1. An original having a pattern to be transferred,wherein the original has a negative effective Poisson's ratio.
 2. Theoriginal according to claim 1, wherein the original comprises astructure having a negative Poisson's ratio.
 3. The original accordingto claim 1, wherein the original comprises a material having a negativePoisson's ratio.
 4. The original according to claim 1, wherein theoriginal comprising: a base portion; and a mesa portion that protrudesfrom the base portion and comprises the pattern, wherein at least a partof the base portion has a negative Poisson's ratio.
 5. The originalaccording to claim 4, wherein the base portion includes the part havingthe negative Poisson's ratio in a region facing the mesa portion, andthe part is not thinner than twice as thick as the mesa portion.
 6. Theoriginal according to claim 5, wherein the part is thinner than anotherpart of the base portion.
 7. The original according to claim 1, whereinthe original is a mold to be contacted with an object to be imprinted.8. The original according to claim 1, wherein the original is a mask viawhich an object is exposed to radiant energy.
 9. A light-transmissiveoriginal having a pattern to be transferred, wherein the original has aneffective Poisson's ratio smaller than that of a quartz glass plate. 10.The original according to claim 9, wherein the original is a mold to becontacted with an object to be imprinted.
 11. The original according toclaim 9, wherein the original is a mask via which an object is exposedto radiant energy.
 12. A method of manufacturing an article, the methodcomprising: transferring a pattern to an object using an original causedto be deformed in accordance with a target shape; and processing theobject, on which the pattern has been transferred, to manufacture thearticle, wherein the original has a negative effective Poisson's ratio.13. A method of manufacturing an article, the method comprising:transferring a pattern to an object using an original caused to bedeformed in accordance with a target shape; and processing the object,on which the pattern has been transferred, to manufacture the article,wherein the original has an effective Poisson's ratio smaller than thatof a quartz glass plate.